/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.flink.streaming.runtime.io;

import org.apache.flink.annotation.Internal;
import org.apache.flink.runtime.checkpoint.channel.InputChannelInfo;
import org.apache.flink.runtime.io.network.partition.consumer.InputGate;
import org.apache.flink.util.Preconditions;

import java.io.IOException;
import java.util.HashSet;

@Internal
interface UpstreamRecoveryTracker {

	void handleEndOfRecovery(InputChannelInfo channelInfo) throws IOException;

	boolean allChannelsRecovered();

	static UpstreamRecoveryTracker forInputGate(InputGate inputGate) {
		return new UpstreamRecoveryTrackerImpl(inputGate);
	}

	UpstreamRecoveryTracker NO_OP = new UpstreamRecoveryTracker() {
		@Override
		public void handleEndOfRecovery(InputChannelInfo channelInfo) {
		}

		@Override
		public boolean allChannelsRecovered() {
			return true;
		}
	};
}

final class UpstreamRecoveryTrackerImpl implements UpstreamRecoveryTracker {
	private final HashSet<InputChannelInfo> restoredChannels;
	private int numUnrestoredChannels;
	private final InputGate inputGate;

	UpstreamRecoveryTrackerImpl(InputGate inputGate) {
		this.restoredChannels = new HashSet<>();
		this.numUnrestoredChannels = inputGate.getNumberOfInputChannels();
		this.inputGate = inputGate;
	}

	@Override
	public void handleEndOfRecovery(InputChannelInfo channelInfo) throws IOException {
		if (numUnrestoredChannels > 0) {
			Preconditions.checkState(!restoredChannels.contains(channelInfo), "already restored: %s", channelInfo);
			restoredChannels.add(channelInfo);
			numUnrestoredChannels--;
			if (numUnrestoredChannels == 0) {
				for (InputChannelInfo inputChannelInfo : inputGate.getChannelInfos()) {
					inputGate.resumeConsumption(inputChannelInfo);
				}
				restoredChannels.clear();
			}
		}
	}

	@Override
	public boolean allChannelsRecovered() {
		return numUnrestoredChannels == 0;
	}
}
